<!DOCTYPE html>
<html lang="zh">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>title</title>
</head>

<style>
  .contaienr {
    width: 100vw;
    height: 100vh;
    background-color: #ccc;
  }

  .base-item {
    position: absolute;
    width: 50px;
    height: 50px;
  }

  .item1 {
    top: 200px;
    left: 20px;
    background-color: yellow;
  }

  .item2 {
    top: 300px;
    left: 100px;
    background-color: palegreen;
  }

  .item3 {
    right: 10px;
    top: 80px;
    background-color: blue;
  }
</style>

<body>
  <div class="contaienr">
    <ul id="ul">
      <li>1</li>
      <li class="hello">2</li>
      <li>3</li>
    </ul>

    <div class="base-item item1"></div>
    <div class="base-item item2"></div>
    <div class="base-item item3"></div>
  </div>
</body>

<script src="./index.mjs"></script>

</html>